The present invention relates to a method for manufacturing a semiconductor device. More particularly, the present invention relates to a method of optimizing pattern decomposition and optical proximity correction for double exposure when fabricating photomasks.
Due to an increase in the integration degree of a semiconductor device, there is a requirement to form finer patterns through a photolithography process. The photolithography process is used to form circuit patterns on a semiconductor wafer, and generally comprises photoresist coating, exposure, development, and the like. A higher resolution, an optimal depth of focus (DOF), etc. are required to form finer patterns using the photolithography process.
As the patterns become finer such that the size of the patterns approaches the limit of resolution, the patterns are likely to become deformed due to light diffraction and interference from adjacent patterns. The influence of adjacent patterns on a target pattern during exposure is referred to as an optical proximity phenomenon.
One method for alleviating the effects of optical proximity is an optical proximity correction (OPC) method in which the optical proximity phenomenon is corrected by adjusting a width of the pattern or by adding a subsidiary pattern. Another method is a double exposure method in which the exposure is separately performed twice such that adjacent patterns are not exposed at the same time.